Generating Trigger (or TTL) from Analogue signal

[ulg]

HI everyone

Well I am investigating the droplet surfing on the vibrating bath. In this case I have to synchronize the camera with the accelerometers.

Accelerometers are connected to the vibrating plate that vibrate sinusoidal with frequency of 80Hz. I am acquiring the acceleration using DAQ NI USB 6212. A camera (Camera Link camera Basler, NI PCIe 1433) is used to acquire the images of the vibrating plate. The frame rate of the camera is 20Hz that controlled by either external signal (TTL) or camera attributes.

I would like to generate a trigger from the DAQ (AI signal) to the camera at first minimum acceleration as shown in attached file. I have also attached the vi file. Could you please let me know if is there anyway we can generate the trigger from the analogue signal.

Cheers

Naresh

[Henrik_Volkers]

A trigger to a peak is  not that easy, ok you can use the zero crossing after derivate .... or use whatever zero crossing and a time/(phase) delay

For a stable solution I would link to the generator that is creating the 80Hz  and use PFI and timer to create a pulse....

[ulg]

Dear Henrik

Thanks for your reply. 

Well i have tried as like you suggested by introducing the delay in my input signal. I am generating a counter signal (40Hz) and connected to NI PCIe 1433 frame grabber. It seems it woking. But image aquasition is not able to aquire the images with 40fps. The frame rate is oscillating bewteen the 36fps to 42fps instead of 40fps.

Parameters:

Exposure time is 1ms

Trigger: external

Action: every image at rising edge. 

The images are acquired by image logging in vision aquisition or by adding IMAQ write file 2. In both cases, the result is same (frame rate instability). 

Could you please help me to solve this probloem. 

Cheers 

Naresh 

[JosD · Accepted solution]

Hi Naresh,

Can you post the updated VI?

[ulg · Accepted solution]

Hi Guys 

Thanks for you help. The problem is solved now. I have changed the exposure controller from free run to trigger.

Cheers 

Naresh